This invention relates generally to the field of rotors and more specifically to a self regulating rotor.
Rotors, with both horizontally and vertically oriented axis, have been designed as windmills and wind turbines to capture energy from the wind. There is a great need for devices that can generate electricity from the energy in the wind. Windmill generated electricity can be stored in batteries. It can replace the need for communities in the third world to purchase kerosene for lighting. Wind generated electricity can also power ultra-violet water disinfection and purification systems which can give third world countries a source of clean drinking water. Windmill generated electricity is a non-polluting source of electricity, and will continue to find greater use through out the world.
Horizontal axis rotor designs have found greater acceptance than vertical axis rotors for use as windmill generators. Horizontal axis rotor wind mills are designed with two or more blades, attached to a rotor hub, similar to the propellers used on propeller driven aircraft. To capture the energy in the wind, horizontal axis rotors need mechanisms to keep their blades facing into the wind. They are designed to operate in environments where the wind is constant in direction and wind speed. Horizontal axis rotor wind mills rotating at high speeds generate strong gyroscopic forces that make them not suitable for use in turbulent winds, where the wind continually changes direction. Horizontal axis wind mills need specific conditions to operate effectively. Horizontal axis rotor wind mills will only operate in a limited range of wind speeds. Horizontal axis rotor windmills are placed on high towers where there is an undisturbed air flow. Horizontal axis rotor windmills are not designed to function well in the disturbed air flows that are found around buildings in cities and urban areas. Placement of propeller type horizontal axis rotor windmills has been resisted by communities because of their appearance and their need to be located on high towers. Horizontal axis rotor windmills need to be sited where the wind is of a minimum velocity and undisturbed to be practical. Horizontal axis rotor wind mills need complex control mechanisms to control their speed of rotation as well as to feather their blades in extreme conditions.
Vertical axis rotors differ from horizontal axis rotors in that they are able to function in wind conditions and site locations that are not practical for horizontal axis rotors windmills to operate in. Vertical axis rotors eliminate some of the problems associated with horizontal axis rotor units, making vertical axis rotors a good alternative to horizontal axis rotors. Vertical axis rotors do not need to continually orient themselves into the wind since their design allows them to accept wind from any direction. Vertical axis rotors can operate in disturbed, turbulent air flows. Vertical axis rotors will operate in a wider range of wind speeds and more varied wind conditions than horizontal axis rotors. Vertical axis rotor type wind mills have the ability to capture wind energy over a greater period of time, which can amount to the extracting of an equal or greater amount of energy from the wind than is captured with a horizontal axis rotor windmill. Vertical axis rotor windmills have inherent advantages of stability due to gyroscopic action of their rotors and simplicity of design due to the avoidance of yaw mechanisms and blade controls. Vertical axis rotors have been designed to increase the energy that can be captured from the wind. Vertical axis rotors that in cross section have the appearance of an S-shape are seen in prior art and will hereafter be referred to as S-shaped rotors.
An S-shaped rotor is disclosed in U.S. Pat. No. 1,646,673 to Wilson. Wilson discloses a vertical axis wind driven turbine windmill, manually adjusted that consists of a plural segmented cylindrical shaped construction, the segments of which may relatively be adjusted to provide an enclosed cylinder, or which may be laterally moved to provide vanes having various degrees of extension, allowing its drive shaft to rotate at varying speeds. In a fully opened configuration the segments form an S-shaped rotor.
In U.S. Pat. No. 1,697,574 to Savonius another vertical axis wind rotor is disclosed. The Savonius device comprises a rotor disposed on the vertical axis which has complementary vertically and longitudinally extending elements rotatable about an individual axis to define in horizontal cross section an essentially S-shaped configuration. This device known as the S-shaped rotor resembles the cylindrical rotor of professor Gustav Magnus and is distinguishable in that oppositely arranged complementary vanes overlap to define between them a centrally S-shaped air passage of consistent area, which Savonius found enhanced the speed and torque developed by the rotor. Among its advantages, the Savonius S-shaped rotor would operate in response to any wind movements, regardless of direction. In U.S. Pat. No. 1,766,765, Savonius provides an improved vertical axis wind turbine wherein he makes provisions for speed control means comprising movable flaps located in transverse relation on the complementary vanes to reduce the speed of rotation of the rotor member during excessive wind movement and velocity.
In U.S. Pat. No. 2,596,726 to Rydell, another vertical axis type wind turbine is shown having telescoping and complementary semicircular elements which are respectively curved and capable of lateral displacement with respect to each other to define the S-shaped rotor in operation. Rydell relies on a rack and pinion linkage for the lateral adjustment of his vanes.
U.S. Pat. No. 3,093,194 to Rusconi also relates to a vertically disposed wind motor having a plurality of vertically disposed curved air foils and which are pivotally linked with respect to each other to define in one configuration an approximate S-shaped rotor. Rusconi controls the speed and energy developed by his device by coiled torsion springs for resisting the relative outward movement of the respective vanes during operation of the device. The spring tends to bring the blades into a configuration promoting the S-shape which optimizes operations of the device.
In U.S. Pat No. 3,942,909 to Vengst, Vengst discloses a vertical axis wind driven rotor having hinged vanes which rotate on individual axis to move from the closed position in which they form a cylinder to open position defining the S-shaped rotor similar to Savonius where the movement of fluid is used to control and regulate a rotors speed of rotation.
And finally in U.S. Pat. No. 4,293,274 Gilman discloses a helically shaped vertical axis S-shaped rotor that regulates its speed of rotation by lateral movements of its vanes from a closed cylinder to open S-shaped rotor through the use of extensive linkages.
Vertical axis S-shaped rotor designs should take advantage of their inherent beneficial characteristics over horizontal axis windmills. They should be adaptable to varying weather and wind conditions and be of a simple design. They should take advantage of their high starting torque at low wind speeds, as well as more aerodynamically efficient shapes in higher wind speeds. They should be able to close into a closed shape to protect them from severe conditions. And finally they should take advantage of rotary movements to facilitate any changes to their shape.
The prior art rotors suffer in at least one respect. For example, Wilson's U.S. Pat. No. 1,646,673 wind turbine is not automatically adjustable and uses a design of laterally shifting paired vanes to change exposed area to the wind. The S-shape is only established when the rotor is totally open. In Savonius's first U.S. Pat. No. 1,697,574, the design cannot close into a closed cylinder. In Savonius's second U.S. Pat. No. 1,766,765, fixed vanes with flaps are used to regulate speed of rotation. This design also cannot close into a cylinder or change vane overlap. Rydell, U.S. Pat. No. 2,596,726, discloses rotors designed for ship propulsion. The rotor described by Rydell uses a relatively complex rack mechanism to cause lateral movements of its vanes and to change vane overlap. Rusconi U.S. Pat. No. 3,093,194 allows its vanes to swing outwardly to control its speed of rotation, losing the S-shape configuration in the process. Vengst's U.S. Pat. No. 3,942,909 uses fluid to control and regulate a rotors speed of rotation. The mass of the fluid increases the rotors inertia and results in a rotor that will not start turning as easily as a rotor without the mass of fluid. Gilman U.S. Pat. No. 4,293,274 uses extensive linkages to facilitate the lateral movements of vanes from a closed cylinder to a S-shape rotor. Finally all of the foregoing devices have relatively complex construction which are expensive to assemble and maintain.